It is common to use butterfly valves in the food and beverage industries to control fluid flows. These valves generally comprise a disk-shaped valve member which rotates in the fluid flow path defined by the valve housing. A handle is attached to a valve stem extending from the valve member and externally of the housing. An operator can rotate the handle to adjust the angular orientation of the valve member and consequently flow rates.
To permit incremental changes in flow rates, it is common to provide such a valve with a 90-degree notch plate. According to conventional practice, the notch plate is essentially an add-on feature which is bolted to a circular flange normally formed with the valve housing and surrounding an exposed end of the valve stem. The notch plate will normally have a part-circular peripheral track extending beyond the flange and formed with regularly spaced-apart notches. A handle formed with a spring-biased mechanism carrying a V-shaped projection cooperates with the notches to permit the handle and consequently the valve member to be rotated in discrete increments and locked in any particular angular position. The notched periphery will normally span a 90 degree sector or arc, which is sufficient to encompass fully open and closed states of the valve.
It is important for an operator to have a positive indication that the valve is either fully open or closed. To that end, portions of the notch plate are commonly bent to positions perpendicular to the general plane of the plate to define a pair of stops at either end of its notched track. This arrangement normally provides for the valve to be fully open when the handle strikes one stop and fully closed when the handle strikes the other stop.
A problem associated with such prior valves is that the handle is confined to a particular range of positions relative to the valve housing. If additional liquid lines must be installed proximate to the line in which the valve is located, or the valve is to be installed in confined surroundings, it can be difficult to orient the handle to provide its required range of movement.